Autoclaves are devices that apply pressure and heat to an object in a controlled environment. Autoclaves are typically steel tanks layered with insulation and having a generally cylindrical shape. Additionally, autoclaves include heat exchangers, fans, pressure hoses, vacuums, and other apparatus to assist in applying pressure and heat to the object. In one application, autoclaves may be used to cure fiber-reinforced composite materials which are placed into the autoclave on a mold tool.
As the size of an autoclave increases, particularly the diameter, the cost of the autoclave increases. A relatively large autoclave with an internal cavity measuring approximately 9 meters (30 feet) in diameter by 24 meters (80 feet) in length may cost tens of millions of US dollars to manufacture. As the diameter increases, the cost of the autoclave may exponentially increase, thus creating a practical limitation on the manufactured size of autoclaves. In addition, each operation cycle of the autoclave includes an associated cost relative to the size of the autoclave. During a cycle, the autoclave may require energy to heat up to approximately 260° C. (500° F.) and pressurize to approximately 690 kPa (100 psi). In addition, cooling agents, such as nitrogen may be used to reduce the cycle time for the autoclave, further increasing the cost per cycle. A cycle for the autoclave mentioned above may cost tens of thousands of US dollars.
The use of new materials to create large objects has presented a unique challenge for autoclave applications. The introduction of fiber-reinforced composite materials has enabled the creation of large single piece objects. These large parts are often advantageous because they do not require fasteners, joints, and other joining devices, and thus have a reduced weight compared to their assembled counterparts. Particularly, in aircraft manufacturing, large single piece objects may be desirable for the above mentioned reasons. Accordingly, there is a continuing need to improve autoclaves to reduce manufacture and cycle costs, and to enable autoclaves to create large objects.